The central theme of this program project is that potent endogenous mechanisms of neuroprotection are encoded in the genome and that the expression of a subset of these genes helps to determine whether cells survive ischemia. The scientific goals are to identify and characterize these genes and the neuroprotective pathways through which their protein products operate. The rationale for this approach is the understanding that the brain's response to injury is an active process that involves new protein synthesis. Identifying gene products that are endogenous neuroprotectants would contribute significantly to our understanding of the pathophysiology of ischemic neuronal injury and would point the way toward new therapeutic approaches to stroke and to related disorders, such as traumatic brain injury. For example, the discovery of a network of transcription factors and target genes that regulate ischemic tolerance in brain would advance pharmacologic efforts to mimic this effect. We will focus on in vivo and in vitro systems wherein endogenous neuroprotection has been induced and the brain has been made tolerant to subsequent ischemic injury (ischemic preconditioning and tolerance). The strategy for discovering neuroprotective genes in ischemia is to use mouse models of ischemic tolerance and microarray analysis to identify genes that are transcriptionally regulated in tolerance (Project 1). Identified genes will then be studied in vitro in models of ischemia and tolerance to characterize and confirm neuroprotective function (Project 2). Finally, gene products that are neuroprotective will be investigated by increasing or reducing their expression in mice in vivo, using pharmacologic and genetic approaches (Project 3). A Genomics Core (Core A) will provide Affymetrix microarray analysis to each project. Our collaborators at Pacific Northwest National Laboratory's Supercomputer and Bioinformatics Division will employ network analysis of gene clusters via conditional probability approaches and functional assignment of unknown genes using analysis of sequence similarities. The Administrative Core (Core B) will coordinate manuscripts, computer connections, data sharing, speaker travel, grants management, and statistical consultation for the interacting laboratories, as well as scientific consultation through internal and external advisory boards.